1. Field of the Invention
The present invention relates to an apparatus for use in servicing hardware used in the drilling and production of fluids from petroleum wells. More particularly, the present invention relates to a field servicing apparatus for lifting, manipulating, and handling the heavy components of hydraulic choke valves.
2. Description of the Related Art
Hydraulic choke devices are commonly used in the oilfield when drilling or treating wells. Herein, the term “hydraulic choke” is taken to refer to a device typically used as a pressure reducing valve with a variety of fluids, such as drilling mud, salt water, oil, gas, and other chemicals that are injected into or withdrawn from a well. “Hydraulic” does not herein refer to the choke actuation means. The service conditions for hydraulic chokes are typically severe, so that the units require frequent field servicing in order to minimize drilling or production downtime. Since the primary components of the choke system, namely the choke valve itself and its associated actuator, are very heavy and field working conditions are often difficult for handling the choke valve, an auxiliary manipulation means is needed to ease choke servicing.
Manipulator devices are use for simplifying the servicing of blowout preventers. However, easy-to-use manipulators for hydraulic choke valves have not been available previously.
Kunkle, U.S. Pat. No. 4,460,154, discloses a pair of telescoping tubes supported in a fixed relationship to a valve. One tube provides a mounting location for a linear actuator, while the other tube is stationary.
Hewitt, U.S. Pat. No. 4,961,538, discloses a valve operation system wherein a linear actuator is provided with a rod in a housing. The system components are held in place by a mounting plate that may be secured to a number of different valves through a valve stem adaptor.
Hewitt, in U.S. Pat. No. 4,611,617, discloses an apparatus mountable on an irrigation pipe for use in controlling valves within the pipe. The apparatus includes a mounting bracket attachable to the valve mechanism and mounting plates for various components of a drive mechanism, including an electric motor, a gear box, a main gear, and a drive chain.
None of these references disclose equipment that will simplify the lifting and manipulation of the heavy components of a choke valve. Power Chokes of Cypress, Texas has used a primitive manipulator for choke valves based on horizontally telescoping support tubes, wherein one tube is mounted to the body of the choke valve and the other tube has its end attached to the separable actuator of the choke valve. The first tube is able to pivot about a nominally vertical axis to permit adjusting the actuator alignment relative to the choke valve. However, this apparatus requires that the tubes remain in the horizontal plane so that high side loads do not cause inadvertent misalignment. Further stick-slip motion of this Power Chokes actuator made manipulation difficult.
A need exists for a simple to install, robust field service device for hydraulic choke valves which is insensitive to stick-slip behavior and misalignment.